b21 := (2,3,4)(5,7,8)(6,9,10)(11,15,16)(12,17,18)(13,19,20)(14,21,22)(24,31,32)
     (25,33,28)(26,34,35)(27,36,37)(29,38,39)(30,40,41)(42,53,50)(43,45,54)
     (44,55,56)(46,57,58)(47,59,60)(48,61,62)(49,63,64)(51,65,66)(52,67,68)
     (69,83,84)(70,85,86)(71,87,88)(72,89,90)(73,91,92)(75,93,94)(76,95,81)
     (77,96,82)(78,97,98)(79,99,100)(80,101,102)(103,115,116)(104,117,114)
     (105,118,108)(106,119,120)(107,121,122)(109,110,112)(111,123,124)(113,
     125,126)(128,133,134)(131,135,136)(132,137,138)(139,141,140)(142,143,144);